More than 40 million Americans under winter storm warnings or weather advisories as heavy snow expected.

Thousands of flights have been cancelled and delayed in the United States due to winter storm Devin, airline monitoring website FlightAware reports, dealing a blow to air travel during peak holiday time.

A total of 1,581 flights “within, into or out of the” US were cancelled and 6,883 delayed as of 4pm US Eastern Time (21:00 GMT) on Friday, according to FlightAware, which describes itself as the world’s largest flight tracking data company.

The delays and cancellations came as the US National Weather ⁠Service warned of winter storm Devin causing “hazardous travel conditions” and heavy snow forecast across parts of the Midwest and northeast.

More than 40 million Americans were under winter storm warnings or weather advisories on Friday, plus another 30 million under flood or storm advisories in California, where a so-called atmospheric river has brought a deluge of rain.

New York City, the largest US city, was bracing for up to 250mm (10 inches) of snow overnight on Friday, the most expected in four years. Temperatures were forecast to drop into the weekend when an Arctic blast is expected to swoop down from Canada.

New York’s John F Kennedy airport, ⁠Newark Liberty international airport and LaGuardia airport warned travellers of potential delays or cancellations. More than half of the flight cancellations and delays took place at these three airports, according to FlightAware.

JetBlue Airways cancelled 225 flights on Friday, the most among the US carriers, closely followed by Delta Air Lines, which cancelled 212 flights. Republic Airways cancelled 157 flights, while 146 were cancelled by American Airlines and 97 by United Airlines.

“Due to winter storm Devin, JetBlue has cancelled approximately 350 flights today and tomorrow, primarily in the Northeast where JetBlue has a large operation,” a JetBlue spokesperson told the Reuters news agency.

On the US West Coast, powerful winter storms brought the wettest Christmas season to Southern California in 54 years.

There was still a risk of more flash flooding and mudslides on Friday despite slackening rain around Los Angeles, the National Weather Service warned.

Firefighters rescued more than 100 people on Thursday in Los Angeles County, with one helicopter pulling 21 people from stranded cars, officials said.